Sunday, Feb. 15, 2015 | 2 a.m.
SALT LAKE CITY — Any future large-scale groundwater pumping in Snake Valley and adjacent arid high-desert areas straddling the Utah-Nevada line is unsustainable, a study commissioned by the Utah Legislature shows.
The study, based on an extensive monitoring network developed by the Utah Geological Survey, also found even current pumping is drawing down the aquifer.
Prompting the study is the Southern Nevada Water Authority's multibillion-dollar pipeline proposal to pump millions of gallons of groundwater a year from the region to the Las Vegas area.
Utah officials fear that tapping water on the Nevada side of Snake Valley would adversely affect ranchers and families on the Utah side.
In addition to Snake Valley, the water district also has filed applications for water rights in Spring, Cave, Dry Lake and Delamar valleys in Nevada. Legal challenges have put the project on hold.
The study found current groundwater use in Snake Valley is slowly depleting the basin-fill aquifer and that present pumping rates will continue to lower groundwater levels and reduce flows of springs, the Deseret News reported.
More ominously, the study concluded future water development and increased pumping in Nevada or Utah would significantly increase the rate and scope of groundwater level decline.
Additional pumping for local agriculture, or export from the area, would harm springs and shallow groundwater that supports habitat of sensitive species and grazing vegetation.
Researchers also found the shallow basin-fill aquifer and deep carbonate rock aquifers are connected. That means increased pumping could draw down both, potentially impacting valleys beyond Snake Valley, said senior scientist Hugh Hurlow of the Utah Geological Survey.
"Groundwater pumping would affect environmental conditions and current and future groundwater use in Snake Valley," he told the Deseret News. "Taken together, the proposals for groundwater development in the region exceed the groundwater available for development. The current ecosystem would be negatively impacted by all but small levels of additional pumping."
Competing studies over the years have led to contradictory conclusions about the amount of water available in the underground reservoirs.
But Hurlow touted the new study, saying the agency's monitoring network includes wells placed in farm and ranch lands, springs and remote sites. A total of 76 wells recorded water levels hourly and six sites featured spring flow gauges.
"The time and resources committed to this study delineates groundwater levels, flow and chemistry in Snake Valley and adjacent basins to a much greater degree than was previously possible," he said.
Last week, the Nevada Supreme Court sent a case about the Las Vegas pipeline proposal back to a state administrator for further administrative review.
The court decided it didn't have jurisdiction over state Water Engineer Jason King's appeal of a previous ruling by a Nevada judge rejecting King's decision to let the pipeline plan proceed in the area straddling the Nevada-Utah border.
The ruling was hailed by project opponents as a victory and by proponents as no big deal.
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